Light-sensitive material with incorporated developer



United States Patent 3,419,395 LIGHT-SENSITIVE MATERIAL WITH INCORPORATED DEVELOPER Anita von Kiinig, Helmut Miider, Hans Ulrich, and Edith Weyde, Leverkusen, Germany, assignors to Agfa Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany No Drawing. Filed Apr. 9, 1965, Ser. No. 447,084 Claims priority, application Germany, Apr. 25, 1964 10 Claims. (Cl. 96-95) ABSTRACT OF THE DISCLOSURE This invention relates to a light-sensitive photographic material which contains developers having methane phosphonic acid groups, which developers are incorporated in the photographic silver halide emulsion layers or in adjacent layers. The emulsion can be developed by contact with aqueous alkali or by heat treatment, and can be used in conventional or difiusion transfer processes.

It is common practice to incorporate developers in photographic emulsion layers but the substances customarily used for this purpose are based on aromatic compounds substituted with hydroxyor amino groups, and do not meet all the requirements. Some of these compounds do not have a sufiicient developer effect Whereas others, which are sufliciently powerful developers, reduce the storage stability of the light-sensitive layers. The reasons for this is the sensitivity to oxidation of the developers by atmospheric oxygen so that the light-sensitive layers are liable to be developed spontaneously Without exposure, a uniform fogging thus being produced.

It is the object of the present invention to provide a photographic material with incorporated developers, which developer has an adequate developing effect and satisfactory stability to oxidation.

It has now been found that 0- or p-arninophenol derivatives or 0- or p-aminonaphthol derivatives or p-phenylenediamine derivatives wherein at least one of the amino groups is substituted with a methane phosphonic acid group exhibit particular utility for this purpose. Preferred are methane phosphonic acid substituents of the formula:

In this formula R =hydr0gen or lower alkyl preferably with 1 to 3 carbon atoms, or an aryl preferably a phenyl or a naphthyl radical, or a cycloalkyl radical such as cyclohexyl or a 5- or 6-membered heterocyclic radical such as fury], thienyl or pyridyl,

R =hydrogen or lower alkyl preferably having 1 to 3 carbon atoms or a phenyl radical.

The substituents R and R may be further substituted as desired. The same applies to the benzene ring moiety of the developer molecule. In choosing the substituents care should, of course, be taken to ensure that the developing effect is not impaired. Especially suitable as substituents are alkyl groups having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, and alkoxy groups the alkyl groups of which also contain 1 to 5, preferably 1 to 3 carbon atoms, halogen such as chlorine or bromine, nitro, cyano and the like.

Patented Dec. 31, 1968 The following are examples of suitable compounds:

III

VII

VIII

XII

III-CHTP OaHz XIII XIV

XVI

XVII

XVIII XIX XXI

XXII

XXIII XXiV OOH;

H CH

| OCH The compounds may be prepared by reacting the corresponding amino phenol, aminonaphthol, or phenylenediamine derivatives with a hydroxymethane phosphonic acid of the following formula III: \OH

In the above formula R and R have the meanings indicated above. For the preparation of the hydroxyrnethane phosphonic acids, the process described in Houben-Weyl, Methods of Organic Chemistry, vol. 12, part 1 (Phosphorus Compounds), pages 363-365, may be used which method consists in reacting the corresponding aldehydes or ketones with phosphorus trichloride followed by hydrolysis.

The detailed preparation of some of the compounds is described below. Other compounds of the type according to the invention are prepared by analogous methods.

COMPOUND X 40 g. of 4-methy-lphenyl-hydroxy-methane phosphonic acid and 22 g. of 4-aminophenol are heated to boiling on a steam bath for /2 hour in 200 -ml. of ethanol. After cooling, the product is filtered under suction and washed several times with hot ethanol and diethyl ether. Yield: 33 g. Melting point: 210 C.

COMPOUND XI 43.6 g. of 4-methoxyphenyl-hydroxy-methane phosphonic acid and 22 g. of 4-aminophenol are heated under reflux for 2 hours in 200 ml. of ethanol. After cooling, the product is precipitated With diethyl ether. For further purification, it is dissolved in methanol and reprecipitated with diethyl ether. It is then suction-filtered and washed with ether. Yield: 32 g. Melting point: 190 C. with decomposition.

COMPOUND XII 40 g. of phenyl methyl hydroxymethanephosphonic acid and 24 g. of S-amino-Z-hydroxytoluene are heated on a steam bath for one hour in 200 ml. of ethanol. After cooling, the product is suction-filtered and Washed first with hot ethanol and then with diethyl ether. Yield: 14 g. Melting point: 178 C.

COMPOUND XXII 24 g. of 4-diethylaminoaniline and 17 g. of hydroxymethane phosphonic acid are heated to boiling for 4 hours under nitrogen in ml. of ethanol. The dark solution is boiled up with animal charcoal and a trace of potassium pyrosulfite and filtered. The compound is isolated as naphthalene-1,S-disulfonate by adding 50 g. of naphthalene-1,5-disulfonic acid. The precipitated product is filtered under suction and Washed with ethanol and diethyl ether. Yield: 60 g. Melting point: above 200 C. with decomposition.

Since some of the compounds decompose on heating with formation of the starting materials, purification by recrystallisation is in many cases not possible. Purification is best effected by precipitation from methanol with diethyl ether or by Washing with ethanol or diethyl ether. In some cases, only resinous non-crystallising products are obtained by the reaction of aminophenol-, or p-phenylene-diamine derivatives with hydroxymethane phosphonic acids. Isolation of the compounds is then effected by converting them into naphthalene-1,5-disulfonates.

The photographic materials according to the invention, containing a developer compound as defined hereinbefore are in principle not subject to any limitations as regards their use for photographic purposes.

The photographic processes can be divided into two main groups, one group comprising processes in which the exposed photographic element is treated with aqueous processing baths and the other methods in which the exposed photographic materials are processed at elevated temperatures without the use of processing baths.

The photographic elements according to the invention are suitable for both groups of processes. It is possible to find out by simple tests which is the optimum developer for the particular photographic process. For processing with aqueous baths it is preferred to use photographic materials which contain aminophenolor aminonaphtholmethane phosphonic acids in which R or R is phenyl. In addition, the layers of these materials are preferably hardened with the usual agents such as Formalin. For heat copying processes, on the other hand, photographic materials containing developers in which R and/or R is hydrogen, phenyl or a lower alkyl radical, preferably methyl are more suitable. In this case it is also preferable to use unhardened layers.

When using wet methods the exposed photographic element can be developed after exposure merely by the action of an alkaline solution. In addition, the developers may also be used in alkaline solutions.

After exposure, the layers according to the invention may be developed in alkaline thiosulphate-containing solutions such as customarily employed for the silver salt diffusion process.

Compared with the known developers such as hydroquinone, aminophenol, p-methylaminophenol and other developers, the developers according to the invention, after they have been incorporated in the emulsion layer, are distinguished not only by better stability to oxidation but also increased utilisation of the sensitivity. The photographic elements of the present invention show practically no fogging, as compared with photographic materials which contain conventional developer compounds.

The light-sensitive materials according to the invention which contain developers having methanephosphonic acid groups are especially advantageous for use in heat copying processes. The principle of such processes is described in German patent specification 888,045. According to this, the material is developed by simple heating after exposure. In this method, development at elevated temperatures can be combined with a transfer process in which either substances from the exposed and developed parts or from the unexposed and undeveloped parts of the photographic material or whole parts of the layer are transferred to a reception material. In this connection, the so-called developer sublimation processes have gained special importance, the principle of which consists in that the unused developer in the unexposed parts are transferred by sublimation to a reception material where they react with a component of the reception material to form a dye image which is a positive, non-reversed copy of the original.

Suitable reception materials may contain:

(1) Substances which produce colored compound by reaction with the developer:

(a) A combination of a color coupler which reacts with the oxidation product of the primary aromatic amino developer to form a dye and an oxidizing agent capable of oxidizing the developer, for instance, a combination of sodium bromate and methylphenyl pyrazolidone (see German Patent No. 895,101);

(b) Nitroso compounds, e.g., sodium o-nitroso benzoate (see German Patent 895,101);

(0) Aromatic diazo compounds in combination with oxidizing agents, e.g., diazo 1 amin0-2-naphthol-4-sulfonic acid and potassium bichromat (see German Patent No. 1,003,577);

((1) Sulfur and alkalipolysulfides (see German Patent No. 1,004,043);

(e) Oxidizing agents, e.g., copper-II-chloride (see German Patent No. 895,101).

In all these cases only the developing agents are transferred to the transfer material and the image obtained consists only of the dye formed in the process.

(2) Development nuclei, e.g., colloidal silver sulfide.

In this case the development is per-formed in the presence of moisture and silver halide is transferred to the transfer material by diffusion.

(3) A combination of 1 and 2. In this case the image consists of transferred silver and of a dye formed in the process.

The reaction components described above can be added to one or more transfer layers which are applied on one or both sides of a suitable support. According to another embodiment the support itself can be impregnated with the compounds required for the image forming reaction.

Since oxidation products of developers containing methanephosphonic acid group are capable of tanning or hardening film-forming proteins, especially gelatin, they can also be used for so-called tanning heat development processes. The properties of the developed layer are in this case so differentiated that either the undeveloped and therefore unhardened parts of the layer or the hardened parts of the layer can be transferred to a transfer material or parts of a transfer layer of the transfer material can be transferred to the unexposed and unhardened parts of the layer. If no special measures are taken, on the other hand, only the unexposed and unhardened parts of the exposed and developed silver halide emulsion layer are transferred and in most cases transfer materials are used that contain substances which react with compounds present in the transferred parts of the silver halide emulsion layer for example the silver halide or the developer, to form colored products. A positive, nonreversed relief image of the original is obtained. Such processes are described in German patent specifications 1,002,628 and 1,150,999, the British patent specifications 821,506 and 984,838, the Belgian patent specifications 638,214, 643,960 and 644,162 and in the published German auslegeschrift 1,189,383.

In the preparation of photographic emulsions the new developers of the invention are preferably added to the washed, finished silver halide emulsion and should of course be uniformly distributed throughout the emulsion. It is convenient to add the developer compounds from solutions in appropriate solvents preferably from water. The concentration of the developer compounds in the silver halide emulsion layers can vary widely, for instance, from about 15150 g. per mol of silver halide. The specific concentration will vary according to the type of lightsensitive material and the reproduction process and according to the effects desired. The suitable and most economical concentration for the given photographic material will be apparent to those skilled in the art upon making the tests customarily used in the art. Preferred are concentrations of 3060 g. per mol of silver halide. Since 1 kg. of an emulsion ready for casting contains about 0.05 to 0.5 mol of silver halide, the quantity of developer in 1 kg. of casting solution corresponds.

The developers according to the invention can also be used in the form of their salts, e.g., alkali metal or alkaline earth salts, or in the form of salt-type addition compounds with acids such as naphthalene-l:S-disulphonic acid or toluene sulphonic acid.

For the preparation of the silver halide emulsion layers, any desired silver halide emulsions may be used such as silver chloride, silver bromide or silver chlorobromide emulsions, which may also contain silver iodide. These emulsions may contain 0.05 to 0.5 mol of silver halide per litre.

As layer forming agents it is possible to use any of the binders customarily used in photographic practice that can be hardened in the heat by oxidation products of the developer and by aldehydes or ketones, e.g., gelatin and zein which may partly be replaced by other layerforming substances, e.g., cellulose derivatives such as carboxyalkylcellulose, particularly carboxymethyl cellulose or methyl hydroxyethyl cellulose, polyvinyl alcohol, polyvinylacetate, polyvinyl acetal, partially hydrolysed polyvinyl acetates, alginic acid and derivatives thereof such as alkali salts or esters particularly alginic acid propylene glycol ester, gelacto-mannanes, polyvinyl pyrrolidone or other natural and synthetic substances.

Photographic layers containing the new developer compounds may be coated on any of the usual photographic materials including for example paper, glass, cellulose ester, particular cellulose acetate or synthetic film-forming resins, such as polystyrene, polycarbonates, in particular of bis-hydr-oxy-phenyl-alkanes, polyesters in particular polyethyleneterephthalates, polyamides, etc. If the photographic material is to be used for heat copying process, care should be taken that the support material is stable at the processing temperature.

The emulsions containing the new developer compounds can be chemically sensitized by any of the accepted procedures. Suitable chemical sensitizers are for example sulfur compound, reducing agents such as stannous salts, polyamines, such as diethyl triamine, salts of the noble metals, such as gold, ruthenium, rhodium, palladium, iridium and platinum.

The emulsions can also be optically sensitized with the usual optical sensitizers such as cyanines, merocyanines, rhodacyanines, neocyanines and the like.

The emulsions can also be stabilized with the usual stabilizers such as organic mercury compounds, triazoles, such as described in the British patent specification 919,- 061, heterocy-clic mercapto compounds, azaindenes, such as described by Birr in Z. wiss. Phot.," vol. 47, 1952, pp. 228.

The emulsions can be hardened with any of the usual hardeners for gelatine, such as formaldehyde and halogen-substituted aliphatic acids, such as mucobromic acid.

The photographic materials containing the developer compounds can also additionally contain matting agents, such as starch ether, dextrine, colloidal silicic acid, finely dispersed silicon oxide, aluminiumoxide, titanium dioxide and the like.

If the photographic materials which contain the new developer compounds are to be used for heat copying processes it has been found particularly advantageous to employ additional substances which provide a desired amount of moisture during the heat development step. Sub substances are compounds which split off water on heating or compounds which increase the residual moisture content of the layer. Compounds of the first mentioned type are urea, caprolactam, fl-nitroethanols or B- cyanoethanols as described in Belgian patent specification 643,960, and salts containing water of crystallization such as sodium citrate or preferably sodium acetate; compounds of the second mentioned type are, for example, polyhydric alcohols such as sorbitol, glycerol or polyethylene glycols. These compounds may be added in such quantities to the casting solution for the negative layer, that the dried layer contain between 0.05 and 25 g. per square meter thereof.

An intermediate layer can be applied between the support and the hydrophilic photographic layer. The intermediate layers are intended to modify the adhesion of a hydrophilic photographic layer, which is in most cases the silver halide emulsion layer, in the desired manner in order, for example, to facilitate the transfer of the unexposed and unhardened or of the hardened parts of the said layer. Especially suitable for such intermediate layers are heat resistant substances such as ethyl cellulose, polyvinylpyrrolidone, zein, polyvinyl acetate, alginic acid derivatives and starch ether or the intermediate layers described in the published German auslegeschrift 1, 189, 383.

Any heat-resistant sheet may be used as transfer material, such as any desired impregnated or untreated paper or also textile fabrics, synthetic resins or metal foils. In the case of coated or treated transfer papers, the layer may contain both additives which supply water and additives which cause the recording to be blackened in known manner, eg N-diethylaminoethanol, triethanolamine, tetramethylammonium hydroxide, pyridine, piperazine, reducing agents and/or sulfur-containing compounds.

The preparation of the positive or of the printing form, i.e. in the transfer process, may be carried out either simultaneously with the developing or at a later time. In addition, several copies may be prepared from one lightsensitive layer either immediately after the first transfer or at a later date. The hardened silver halide emulsion layer may be fixed in a fixing bath or stabilized by stabilizers. The negative images obtained by heat development are fairly insensitive to light and therefore the process is suitable for registration purposes, which require a quick access to the recorded signal.

The image-forming process is generally accomplished by first exposing the light-sensitive negative material to an object to be reproduced. Thereafter, the exposed material is brought into contact with the light-insensitive transfer material.

The combination of both materials is subjected to heat development by heating to a temperature of between to 200 C. preferably to C. for a period of time of between /2 second and 3 minutes.

In some cases it is advantageous to develop the negative alone by application of heat, contact the developed emulsion layer with the transfer material and subject the combination again to a heat treatment.

Example 1 To 1,000 ml. of a silver bromide emulsion are added 20 ml. of saponin solution (5% in water), 20 mg. of 1-phenyl-5-mercaptotetrazole (1% in ethanol), 3 ml. of formalin (30% in water) and 26.8 g. of Compound X.

The emulsion is applied in known manner onto barytacoated paper and dried. After exposure through a step wedge having a logarithmic increase in blackening of 0.15, the paper is developed for 90 seconds in 0.1 N sodium hydroxide solution and then fixed and watered in the usual way.

A control material contains instead of Compound X the equimolar quantity of 4-aminophenol.

The fogging values for both materials are: 4-aminophenol: 0.16, Compound X: 0.05.

The photographic material containing the compound according to the invention has a higher speed by three steps at the threshold of the characteristic curve with otherwise the same gamma and contrast.

Example 2 In the silver halide emulsion of Example 1, Compound X is replaced by 28.2 g. of Compound XI and the emulsion is applied in a similar manner onto baryta-coated paper. After photographic processing, the material has a fogging of 0.06. If the compound according to the invention is replaced by an equimolar quantity of N-methylaminophenol, the fogging for the same gamma is 0.17.

9 Example 3 The procedure for preparing the photographic material is the same as in Example 1, using 26.8 g. of Compound XIV. After photographic processing, the fogging is 0.07. A material prepared with an equimolar quantity of p-benzylaminophenol has a fogging of 0.15.

Example 4 Example 5 To 1 litre of a gelatine silver chloride emulsion are added mg. of 1-phenyl-S-mercaptotetrazole 1% in ethanol), 150 g. of sodium acetate (cryst.), 5.5 g. of cyclohexanone bisulfite, g. of starch, 20 g. of colloidal silicic acid, 5 ml. of a 30% aqueous solution of saponin and 20 g. of Compound XXV or Compound XXVI.

The pH of the emulsion is adjusted to 4.9 with sulfuric acid. The emulsion is applied in known manner to barytacoated paper and dried.

Reception material I A solution of 20 g. of sodium bromate, 30 g. of methylphenyl yrazolone, 30 g. of a polyethylene-glycol having an average molecular weight of about 1500 and 30 g. of polyethylene glycol having an average molecular weight of about 400 in 1 litre of water is applied in known manner to an unbaryta-coated paper and dried. The exposed light-sensitive layer and the reception material are brought into contact and subjected for 2 to 30 seconds to a temperature of 110 to 200 C., preferably 120 to 150 C., by means of a heat developing apparatus without moisturizing device or by means of a high gloss press or drying drum. The positive may be exposed to a higher temperature than the negative. On separation of the papers, a red image is obtained.

Reception material II A solution of 8 g. of gallactomannane, 1.1 g. of car- 'boxymethyl starch ether, 200 g. of potassium bromate, 0.8 g. of copper sulphate and 4 mg. of polyethylene glycol having an average molecular weight of 200, 0.8 g. of a 50% solution of a wetting agent consisting of a combination of parafiin sulfonic acid sodium and an alkylaryl polyglycol ether and ml. of a 15% silicic acid sol (having a surface of 200 m? per gram), in one litre of water are adjusted to pH 3.5 with sulfuric acid and applied in known manner to a paper and dried. A greyish black image is obtained when used as a transfer sheet.

Reception material III A paper is impregnated with a solution of 100 g. of sodium bromate, 1 g. of ammonium vanadate, 20 ml. of a polyethylene glycol having an average molecular weight of 300 and 0.2 g. of a solution of a wetting agent consisting of a combination of parafiin sulfonic acid sodium and an alkyl-phenyl polyglycol ether, and 80 ml. of a 15% silicic acid sol (having a surface of 200 m. per gram) in 1.5 litres of water, and dried. Working up is carried out as described above. A black brown image is obtained when used as a transfer sheet.

Example 6.Light-sensitive material To 1 litre of a silver chloride emulsion are added 0.1 g. of benztriazole (5% in ethanol), 125 g. of sodium acetate, 5 g. of cyclopentanone bisulphite, 15 g. of the Compound I or II, 100 ml. of a 15% solution of a silicic acid sol (having a surface of 200 m. per gram). The pH is adjusted to 5.0 with citric acid. The emulsion is applied in known manner to a baryta-coated paper and dried.

Transfer material IV A solution of 20 g. of alginic acid propylene glycol ester, 4 g. of gelatin, 5 g. of polyvinyl acetate, 0.6 g. of colloidal silver sulphide, 0.08 g. of 3-mercapto-4z5-dimethyltriazole-(1:2:4), 2 ml. of a polyethylene glycol having an average molecular weight of about 400 and 2 ml. of 5% saponin in 1 litre of water are applied to a paper and dried.

The exposed light-sensitive layer and the transfer layer are brought into contact and passed through a heat developing apparatus with moisturizing device for 10 seconds at a roller temperature of 125 C. After a further 15 seconds contact time, the layers are separated. A black brown image is obtained.

Using the transfer materials II and III described in Example 5, a black brown dye image is obtained upon processing the light-sensitive material of Example 6 in the manner described in Example 5 with the transfer materials II and III.

Instead of the developer substances mentioned above, 20 g. of Compound XV or 20 g. of Compound XIX may be added to the light-sensitive layer.

Example 7.Light-sensitive material To 1 litre of a silver chloride gelatine emulsion are added 30 mg. of l-phenyl-S-mercaptotetrazole (1% in ethanol), 100 g. of sodium acetate (cryst.), ml. of a 15 aqueous silicic acid sol (having a surface of 200 m? per gram), 5 g. of cyclohexanone bisulfite, 10 g. of Compound I or II, 5 ml. of polyethylene glycol having an average molecular Weight of 400 and 5 ml. of saponin (30%) in water. The pH is adjusted to 5.3 with sulfuric acid. The emulsion is applied to paper in known manner and dried.

A dark brown image is obtained with the transfer materials II and III described in Example 5, employing the processing conditions described there. With the transfer material IV described in Example 6, a black brown image is obtained.

Instead of the developer substances mentioned above, 15 g. of Compound XIII may be added to the light-sensitive layer.

The light-sensitive materials prepared according to Example 7 are much more stable in storage than the corresponding known light-sensitive materials which contain p-methylaminophenol sulfate and are provided with potassium metabisulfite as protection against spontaneous development. In principle, for the process of the invention there may also be used light-sensitive materials which contain the developer substances not in the lightsensitive layer but in an adjacent auxiliary layer.

Example 8 A paper is coated with a solution of 4.2 g. of sodium alginate, g. of maltose and 5 g. of Compound II or XXV in 1 litre of water.

This material is further coated with the following silver halide emulsion: 1 kg. of silver chloride gelatine emulsion containing 2.2 mols of AgCl per kg. of gelatine, 25 mg. of 1-phenyl-S-mercaptotetrazole dissolved in alcohol, g. of sodium acetate (cryst.), 5 g. of finely dispersed silicon oxide, 10 g. of Compound II or XXV, 4 g. of cyclohexanone bisulfite and 5 ml. of saponin (30% aqueous solution).

Processing is carried out as described in Example 5 or alternatively the exposed light-sensitive material is developed and then brought into contact with the transfer material II or III of Example 5. After separation of the papers, a dark brown or greyish black image is obtained.

Example 9 To 1 kg. of any desired silver bromide gelatine emulsion are added 200 mg. of 4-hydroxy-6-methyl-l,3,3a,7- tetraazaindene dissolved in alcohol, 120 g. of sodium acetate (cryst.), 2 g. of cyclohexanone bisulfite, and 10 g. of Compound II, ml. of saponin (30% aqueous solution). The pH is adjusted to 5.8. The emulsion is applied in known manner to a carrier layer and dried.

Processing.-The exposed light-sensitive material is brought with its rear surface into contact with a surface of metal or synthetic resin heated to 90 to 200 C. or with a liquid heat transfer material for 0.5 to 60 seconds. As developing devices may be used heatable presses, drying drums, rollers or the apparatus described in British patent specification 983,802 or alternatively the exposed lightsensitive material which has been subjected for about to 180 seconds to infrared radiation.

The resulting material which is tanned at the exposed and developed areas has little sensitivity to light. It can be stabilized by fixing and watering or by bathing in an alcoholic solution of 2,5-dimercapto-thiadiazole-1,3,4 or 1- phenyl-S-m-ercaptotetrazole.

Example 10 A paper is coated with a dispersion of 6.5 g. of sodium alginate, 100 g. of polyvinyl acetate, 100 g. of sodium acetate (cryst.), citric acid to adjust the dispersion to pH 5.1, and 5 ml. of saponin solution (5% in water), in 1.25 litres of water.

This material is further coated with the following silver halide emulsion; 1 kg. of silver chloride gelatine emulsion containing 2.2 mols of AgCl per kg. of gelatine, 200 mg. of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (dissolved in ethanol), 50 mg. of benztriazole (dissolved in ethanol), 110 g. of sodium acetate (cryst.), 2 g. of cyclopentanone bisulfite, 10 g. of Compound I, 3 g. of finely dispersed silicone oxide, and 5 ml. of saponin (5% aqueous solution).

The pH is adjusted to 4.9 with citric acid. The emulsion is applied in known manner to the intermediate layer and dried.

Processing-The exposed light-sensitive material is developed as described in Example 9. A negative silver image tanned in the exposed areas is obtained. The developed material is brought into contact with a transfer material for producing a non-reversed positive copy, the materials being exposed to a temperature of 100 to 200 C., preferably 14-0 to 180 C., so that the parts of the nonexposed light-sensitive materials, which are not tanned are transferred to the transfer material and blackened there. The two papers are separated immediately after heating, a black positive image of the original being obtained on the transfer material. In the transfer process, dependent on the apparatus used, the negative or the transfer material or the rear surface of both papers may be slightly moistened by water or steam, this improving mainly the ability of the papers to lie flat. Suitable transfer materials are described in German patent specification No. 1,166,620. These may, for example, be prepared according to the following prescription:

Transfer material.A blank paper is coated with the following solution and dried: 70 g. of polyvinyl alcohol, 10 g. of thiosemicarbazide, 8 g. of benzene sulfonic acid hydrazide, and 10 g. of an ester wax (for instance a wax which is sold by Farbwerke Hoechst under the name Wax KSE), in 1 litre of water.

Example 11 A paper is coated with a solution of 36 g. of polyvinyl alcohol, 50 g. of sodium acetate (cryst.), citric acid to 12 adjust the pH to 5.3, 15 g. of Compound XIX, and 2 g. of cyclohex-anone bisulfite in 1 litre of water.

This material is further coated with the following silver halide gelatine emulsion: 1 kg. of silver chloride emulsion containing 2.2 mols of AgCl per kg. of gelatine, 200 mg. of 4-hydroxy-6-methyl-l,3,3a,7-tetraazaindene and 20 mg. of N-phenyl-N'-(5)-benztriazolylurea, dissolved in alcohol, g. of sodium acetate (cryst.), 5 g. of finely dispersed silicon oxide, and 5 ml. of saponin (30% aqueous solution).

Processing is carried out as described in Example 10.

Example 12 A paper is coated with a dispersion of 1.8 g. of gallactomannane, 17.5 g. of polyvinyl acetate, 15 g. of cane sugar, 10 g. of Compound II, 2 g. of cyclohexanone bisulfite, and 5 ml. of saponin (5% aqueous solution), in 1 litre of water.

This material is further coated with the silver halide gelatine emulsion given in Example 11.

Instead of Compound II, equimolar quantities of Compound XV may be added to the intermediate layer. Processing is carried out as described in Example 10.

Example 13 A paper is coated with a dispersion of 10 g. of alginic acid propylene glycol ester, 200 g. of polyvinyl acetate, 20 g. of cane sugar, 10 g. of Compound II, and 8 ml. of saponin (5% aqueous solution), in 1.5 litres of water.

This material is further coated with the silver halide emulsion described in Example 11.

Processing.--The exposed negative material is developed in contact with a rice paper as customarily used in screen printing, using one of the apparatus mentioned in Example 9. After development, the rice paper is either slightly moistened with water or the negative paper combination bathed in water. The moistened rice paper can now be separated from the light-sensitive material. The exposed and tanned parts of the silver halide gelatine emulsion layer are now on the rice paper and the unexposed, untanned parts of the emulsion layer remain on the intermediate layer, The transferred portions of tanned gelatine form on the rice paper a layer which is impermeable to dyes thus providing a printing form suitable for screen printing.

Example 14 70 g. of sodium polya-crylate and 2 g. of colloidal silicic acid are dissolved in 1 litre of water. This solution is applied to a support and dried.

Processing.The light-sensitive material described in Example 13 is exposed to a negative original to be reproduced. The exposed light-sensitive material is developed in contact with the transfer material. After separation of the two materials, a positive copy of the negative original is obtained since the tanned parts of the silver halide gelatine emulsion layer are transferred to the transfer material.

Instead of the silver chloride emulsion mentioned in the examples, a silver chlorobromide emulsion as customarily used for enlarging papers can be used.

We claim:

1. A light-sensitive material having at least one supported light-sensitive silver halide emulsion layer which contains an effective amount of a developer compound of the group consisting of an o-aminophenol, a p-aminophenol, an o-aminonaphthol, a p-aminonaphthol and a pphenylenediamine, at least one of the amino groups of the developer compound being substituted by a methane phosphonic acid group.

2. A light-sensitive material as defined in claim 1, in which the methane phosphonic acid group has the formula 5. Light-sensitive material according to claim 1, characterised in that the developer has the formula HOQ-N-(F-P 0311i 7. A process for developing an exposed silver halide emulsion on a support, which comprises eifecting the development with a developer compound of the group consisting of an o-arninophenol, a p-aminophenol, an

aminonaphthol, a p-aminonaphthol and a p-phenylenediamine at least one of the amino groups of the developer compounds being substituted by a methane phosphonic acid group.

8. A process as defined in claim 7, in which the methane phosphonic acid group has the formula wherein R represents a member of the group consisting of hydrogen, lower alkyl, phenyl, naphthyl, eycloalkyl, furyl, thienyl, and pyridyl, and R stands for a member of the group consisting of hydrogen, lower alkyl and phenyl.

9. A light-sensitive material having a light-sensitive silver halide emulsion layer in intimate relation with an efiective amount of an o-aminophenol, p-aminophenol, oaminonaphthol, p-aminonaphthol or p-phenylenediamine developer in which an amino group of the developer is substituted by a methane phosphonic acid group.

10. A light-sensitive material as defined by claim 11 in which the developer is in a layer different from but contiguous to the emulsion layer.

References Cited UNITED STATES PATENTS 2,618,657 11/1952 Vaughn et a1 9666 NORMAN G. TORCHIN, Primary Examiner. G. COHN, Assistant Examiner.

U.S. C1.X.R. 9666 

